1. Field of the Invention
This invention pertains to connections of tubular products, such as for example liquid sight monitors and more particularly to how such products are connected in either a liquid flowing system or as a level gauge with respect to a liquid storage system.
2. Description of the Prior Art
As an example of tubular products that can be joined or connected in the manner hereinafter described, liquid sight monitors primarily include both sight flow indicators and liquid level gauges. A sight flow indicator is employed in a flowing liquid system, or in a bypass connection to such a system, to show that fluid is flowing and in some cases to show if a condition has changed, such as the liquid changing color. A liquid level gauge is employed to monitor the level of liquid stored in an opaque tank or other similar vessel. Usually, one or more gauges are connected to vertically separated piping from the vessel to give a visual indication of the level of the liquid within the vessel.
The monitor employs a transparent element, usually glass, to permit visual observance of the liquid. It should be further noted that the liquid is often under pressurized condition and frequently the vessel is part of a vehicle, such as a tank on a tank car. In many of such applications, one or both ends of the sight monitor is mounted in a severely difficult installation environment, where the sight monitor might work loose. It could be very inconvenient or very dangerous if such event occurred.
Prior art connections include the tubing adapter shown in U.S. Pat. No. 3,381,976. Such an adapter has a plurality of pressure energized O-ring seals operating with accommodating grooves, the ring seals bearing against the surface of the glass. Such a connector forms satisfactory connection provided the glass is not appreciably out-of-round and there is not a great deal of internal pressure operating on the glass in such a way that the glass is vertically pressured out of the connector.
Sight monitors are not always simple one-glass devices. They are sometimes made of two concentric glass tubes, the outer tube providing means to environmentally isolate or protect the inner tube with the liquid. That is, in a concentric tube installation, the volume between the tubes can be purged of moisture and air or can be replaced with an inert gas. Such a sight monitor does not fog up like a single glass device might. Furthermore, protective shields, such as tubular metallic shields with one or more slot openings, can be provided to keep the glass tube or tubes from being broken.
U.S. Pat. No. 4,345,468 entitled "Liquid Sight Monitor", issuing Aug. 24, 1982 in the name of William A. Jackson, and commonly assigned herewith, discloses the use of connector ends having O-ring seals in appropriate grooves so as to permit O-ring sealing against an internal tube and O-ring sealing against an outer tube. The disclosure set forth in U.S. Pat. No. 4,345,468 is adopted herein by reference for all purposes.
Again, however, if the dimensions of the tubes are not held within close tolerance, or if they are out-of-round of if the connector portion with the O-ring grooves is not perfectly dimensioned, then there is danger of a loose seal. No provisions are provided to adjust the seal in the presence of an improperly sized tube or connector component or in the presence of pressure being exerted to separate the connector from the tube or tubes it holds. Moreover, such a structure requires the resilient O-rings to have separate, non-resilient support structure apart from the O-rings themselves to provide stabilizing support of the O-rings in their places, which structures in the '468 patent are the connector ends and the splicer connector having grooves therein for accommodating and constraining the O-rings so that they are able to correctly function.
Therefore, it is a feature of the present invention to provide an improved one piece connector for a tubular product such as a sight flow monitor that is secured at least at one end in such a way so as to accommodate to a limited range of sizes and out-of-round conditions of a tube.
It is another feature of the present invention to provide an improved connector that pressure seals against the end of a liquid sight monitor, particularly when the liquid system being monitored is under pressure.
It is still another feature of the present invention to provide an improved connector that pressure seals against both tubes of a concentric tube liquid sight monitor, particularly when the liquid system being monitored is under pressure.